1. Field of the Invention
This invention relates to a computer-implemented method and a system for locating an indoor object, more particularly to a computer-implemented method and a system involving fusing radio frequency (RF) coordinate information and motion sensor coordinate information through fusion techniques for locating an indoor object.
2. Description of the Related Art
A conventional system for locating an indoor object, such as that disclosed in “A pyroelectric infrared sensor-based indoor location-aware system (PILAS) for the smart home,” Lee et al., IEEE Transactions on Consumer Electronics, Volume 52, Issue 4, November 2006 Page(s): 1311-1317, utilizes a plurality of pyroelectric infrared (PIR) sensors to locate the indoor object. Although the aforesaid conventional PILAS can be used to estimate the position of the indoor object, it has flaws when a plurality of indoor objects are to be located. For example, referring to FIG. 1, when PIR sensors a and b are on and PIR sensor c is off, the PILAS is unable to determine whether there are two indoor objects moving in sensing areas A and B, respectively, or only one indoor object moving in overlapped region AB of sensing areas A and B.
Another conventional system for locating an indoor object involves the use of RF locating techniques, such as the Received Signal Strength (RSS) approach. The RSS approach utilizes at least three reference node RF transceivers, each of which is placed at a pre-determined position, and a blind node RF transceiver carried by the indoor object to locate the indoor object. The RSS approach estimates the position of the indoor object according to at least three RSS signals, each of which is related to a distance between a respective one of the reference node RF transceivers and the blind node RF transceiver. The RSS approach is disadvantageous in that the propagation of radio signals is easily affected by indoor obstacles, such as furniture and people in the indoor area, as well as by other electronic devices, which can result in estimating error and Non-Line-of-Sight (NLOS) error. NLOS error is attributed to signal interference caused by indoor obstacles, and gets worse when the number of indoor obstacles is increased.